2013•Zhongguo shengwuzhipinxue zazhiRequires access
Protection level of neutralizing antibody against enterovirus 71
Junzhi Wang
Open publisher page 0 citations
Abstract
Objective To measure the neutralizing antibody titer against enterovirus 71(EV71) in suckling mouse model,healthy infants and the target population after immunization and provide a basic data for determination of protection level of EV71 vaccine.Methods The neutralizing antibodies in six serum samples against various EV71 strains were quantified accurately,and evaluated for protection level by challenge test in two suckling mouse models.The neutralizing antibodies in serum samples of healthy infants and the target population after immunization were quantified accurately by standardized neutralization test in vitro and the standard substances for quantification of EV71 neutralizing antibody.Results The protection levels of EV71 neutralizing antibodies in 6 serum samples were similar in challenge tests in two suckling mouse models,with ED50 values of 10 ~ 50 U and 6.1 ~ 54.2 U,respectively.The antibody positive rates of infants at ages of 7,12 and 24 months were 45.0%,48.8% and 56.8%,while the neutralizing antibody titers in antibody positive infants were 113.8,120.3 and 330.6 U / ml(with a GMT of 173.2 U / ml),respectively.However,the antibody positive rate and the neutralizing antibody titer were 86.7% and 114.3 U / ml respectively in the infant's mothers.After immunization with two doses of vaccine at high and moderate dosages,the neutralizing antibody positive rates in infants were 100%,while the neutralizing antibody titers were 356.0 and 1 136.2 U / ml,respectively,which were 2.1 ~ 6.6 times higher than those in infants infected naturally.Conclusion The protection levels of EV71 neutralizing antibody on suckling mouse model,infants and the target population after EV71 vaccination were quantified as the unit of U / ml by using standardized neutralization test in vitro and the standard substances for quantification of EV71 neutralizing antibody,which provided a basis for determination of protection level of neutralizing antibody in vaccinated population.